/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.ssi;

import org.apache.tomcat.util.ExceptionUtils;

import javax.servlet.ServletContext;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Locale;
import java.util.TimeZone;

/**
 * A HttpServletResponseWrapper, used from
 * <code>SSIServletExternalResolver</code>
 *
 * @author Bip Thelin
 * @author David Becker
 */
public class ResponseIncludeWrapper extends HttpServletResponseWrapper {
	/**
	 * The names of some headers we want to capture.
	 */
	private static final String CONTENT_TYPE = "content-type";
	private static final String LAST_MODIFIED = "last-modified";
	private static final DateFormat RFC1123_FORMAT;
	private static final String RFC1123_PATTERN = "EEE, dd MMM yyyy HH:mm:ss z";

	static {
		RFC1123_FORMAT = new SimpleDateFormat(RFC1123_PATTERN, Locale.US);
		RFC1123_FORMAT.setTimeZone(TimeZone.getTimeZone("GMT"));
	}

	protected long lastModified = -1;
	/**
	 * Our ServletOutputStream
	 */
	protected ServletOutputStream captureServletOutputStream;
	protected ServletOutputStream servletOutputStream;
	protected PrintWriter printWriter;
	private String contentType = null;
	private ServletContext context;
	private HttpServletRequest request;

	/**
	 * Initialize our wrapper with the current HttpServletResponse and
	 * ServletOutputStream.
	 *
	 * @param context                    The servlet context
	 * @param request                    The HttpServletResponse to use
	 * @param response                   The response to use
	 * @param captureServletOutputStream The ServletOutputStream to use
	 */
	public ResponseIncludeWrapper(ServletContext context,
	                              HttpServletRequest request, HttpServletResponse response,
	                              ServletOutputStream captureServletOutputStream) {
		super(response);
		this.context = context;
		this.request = request;
		this.captureServletOutputStream = captureServletOutputStream;
	}

	/**
	 * Flush the servletOutputStream or printWriter ( only one will be non-null )
	 * This must be called after a requestDispatcher.include, since we can't
	 * assume that the included servlet flushed its stream.
	 */
	public void flushOutputStreamOrWriter() throws IOException {
		if (servletOutputStream != null) {
			servletOutputStream.flush();
		}
		if (printWriter != null) {
			printWriter.flush();
		}
	}

	/**
	 * Return a printwriter, throws and exception if a OutputStream already
	 * been returned.
	 *
	 * @return a PrintWriter object
	 * @throws java.io.IOException if the outputstream already been called
	 */
	@Override
	public PrintWriter getWriter() throws java.io.IOException {
		if (servletOutputStream == null) {
			if (printWriter == null) {
				setCharacterEncoding(getCharacterEncoding());
				printWriter = new PrintWriter(
						new OutputStreamWriter(captureServletOutputStream,
								getCharacterEncoding()));
			}
			return printWriter;
		}
		throw new IllegalStateException();
	}

	/**
	 * Return a OutputStream, throws and exception if a printwriter already
	 * been returned.
	 *
	 * @return a OutputStream object
	 * @throws java.io.IOException if the printwriter already been called
	 */
	@Override
	public ServletOutputStream getOutputStream() throws java.io.IOException {
		if (printWriter == null) {
			if (servletOutputStream == null) {
				servletOutputStream = captureServletOutputStream;
			}
			return servletOutputStream;
		}
		throw new IllegalStateException();
	}

	/**
	 * Returns the value of the <code>last-modified</code> header field. The
	 * result is the number of milliseconds since January 1, 1970 GMT.
	 *
	 * @return the date the resource referenced by this
	 * <code>ResponseIncludeWrapper</code> was last modified, or -1 if not
	 * known.
	 */
	public long getLastModified() {
		if (lastModified == -1) {
			// javadocs say to return -1 if date not known, if you want another
			// default, put it here
			return -1;
		}
		return lastModified;
	}

	/**
	 * Sets the value of the <code>last-modified</code> header field.
	 *
	 * @param lastModified The number of milliseconds since January 1, 1970 GMT.
	 */
	public void setLastModified(long lastModified) {
		this.lastModified = lastModified;
		((HttpServletResponse) getResponse()).setDateHeader(LAST_MODIFIED,
				lastModified);
	}

	/**
	 * Returns the value of the <code>content-type</code> header field.
	 *
	 * @return the content type of the resource referenced by this
	 * <code>ResponseIncludeWrapper</code>, or <code>null</code> if not known.
	 */
	@Override
	public String getContentType() {
		if (contentType == null) {
			String url = request.getRequestURI();
			String mime = context.getMimeType(url);
			if (mime != null) {
				setContentType(mime);
			} else {
				// return a safe value
				setContentType("application/x-octet-stream");
			}
		}
		return contentType;
	}

	/**
	 * Sets the value of the <code>content-type</code> header field.
	 *
	 * @param mime a mime type
	 */
	@Override
	public void setContentType(String mime) {
		contentType = mime;
		if (contentType != null) {
			getResponse().setContentType(contentType);
		}
	}

	@Override
	public void addDateHeader(String name, long value) {
		super.addDateHeader(name, value);
		String lname = name.toLowerCase(Locale.ENGLISH);
		if (lname.equals(LAST_MODIFIED)) {
			lastModified = value;
		}
	}

	@Override
	public void addHeader(String name, String value) {
		super.addHeader(name, value);
		String lname = name.toLowerCase(Locale.ENGLISH);
		if (lname.equals(LAST_MODIFIED)) {
			try {
				synchronized (RFC1123_FORMAT) {
					lastModified = RFC1123_FORMAT.parse(value).getTime();
				}
			} catch (Throwable ignore) {
				ExceptionUtils.handleThrowable(ignore);
			}
		} else if (lname.equals(CONTENT_TYPE)) {
			contentType = value;
		}
	}

	@Override
	public void setDateHeader(String name, long value) {
		super.setDateHeader(name, value);
		String lname = name.toLowerCase(Locale.ENGLISH);
		if (lname.equals(LAST_MODIFIED)) {
			lastModified = value;
		}
	}

	@Override
	public void setHeader(String name, String value) {
		super.setHeader(name, value);
		String lname = name.toLowerCase(Locale.ENGLISH);
		if (lname.equals(LAST_MODIFIED)) {
			try {
				synchronized (RFC1123_FORMAT) {
					lastModified = RFC1123_FORMAT.parse(value).getTime();
				}
			} catch (Throwable ignore) {
				ExceptionUtils.handleThrowable(ignore);
			}
		} else if (lname.equals(CONTENT_TYPE)) {
			contentType = value;
		}
	}
}
